1. Field of the Invention
This invention relates to sewer trap priming valves i.e. to valves for use in charging water into sewer line water traps to prevent the escape of sewer gas.
2. Description of the Related Art
In accordance with conventional building practices, automatic means is provided for supplying water to each sewer line water trap of a structure, automatically and periodically, to ensure that the trap will be operative at all times. It is usual to interconnect the pressured house water line and the sewer trap with a spur water line, and to include in the spur line a priming valve designed to admit water to the trap as required to keep it full and operative.
However, the prior art sewer trap priming valves are subject to failure for various reasons. Since they are required to operate unattended over a long period of time, their moving parts are subject to corrosion. If of the common category actuated by springs, they eventually fail because the springs rust and break. Some categories of priming valves are not subject to adjustment, either initially or during their service life as required by wear or by variations in water line pressure.
Watts U.S. Pat. No. 3,422,835 addresses these problems and provides a partial solution. However, over time a problem is presented in the operation of the Watts valve.
Referring to FIG. 3 of Watts, an adjustment screw 52 drives an eccentric pin 50 working in annular groove 46. Turning the screw adjusts the position of the valve body (tube 32). In this manner the valve may be adjusted from time to time for changes in house line pressure and wear. A lock nut 56 secures the screw, and hence the eccentric pin, in a selected position of valve adjustment.
However, over a period of time, repeated adjustments often result in backing off screw 52 to such an extent that eccentric pin 50 is withdrawn completely from operating groove 46 with the result that the groove drops out of registry with the pin. It then becomes impossible to reinsert the pin and the valve becomes inoperable.
It is the general purpose of the present invention to provide an adjustable sewer line water trap valve having all the advantages of the water valve, but one in which the foregoing problem is overcome.